1. Field of the Invention
The present invention relates to a dressing device and a dressing method for a centerless grinding machine, more specifically to a dressing technology for either dressing or truing a grinding face of a grinding wheel and a rotary supporting face of a regulating wheel of a centerless grinding machine, efficiently and with high accuracy.
2. Description of the Related Art
A Centerless grinding machine is a system for grinding the outside cylindrical surface of a work piece (hereinafter referred to as "work") by a grinding wheel while rotatably supporting that outside cylindrical surface between the grinding wheel, a regulating wheel and a blade (bearing plate). In this centerless grinding machine, dressing by a dressing device is performed at prescribed intervals to a grinding face of the grinding wheel and a rotary supporting face of the regulating wheel, in order to constantly secure high grinding accuracy and high grinding efficiency.
A conventional centerless grinding machine was provided with special dressing devices for the grinding wheel and the regulating wheel respectively, and the dressing of the grinding face of the grinding wheel and that of the rotary supporting face of regulating wheel used to be performed independently of each other.
Moreover, said two dressing devices were provided on the opposite sides of the grinding position i.e. on the outsides of the grinding wheel and the regulating wheel respectively, not to disturb the grinding by the grinding wheel and the regulating wheel.
However, such a conventional construction has presented the following problems and there has been a desire for improvement about the construction of this point:
(1) Equipment cost of the grinding machine increases due to necessity of two dressing devices.
(2) The grinding machine increases in size and complicates in structure, because installation spaces of said two dressing devices are provided on the outsides of the grinding wheel and the regulating wheel respectively.
(3) In a radial feed type centerless grinder, relative positioning in axial direction of the grinding wheel and the regulating wheel is extremely important, because the grinding face of the grinding wheel and the rotary supporting face of the regulating wheel have a profile fit for the outside cylindrical surface of the work. However, with a construction in which the dressing is performed individually on the grinding wheel side and the regulating wheel side as described above, this relative positioning in the axial direction becomes difficult, taking lots of time for the change of the setup, etc. This problem was conspicuous especially in a case where said grinding face and rotary supporting face have a complicated profile.